Abstract
OBJECTIVE: Although the mobile-bearing Oxford unicompartmental knee arthroplasty (OUKA) seems an appropriate procedure to treat spontaneous osteonecrosis of the knee (SONK), aseptic tibial component loosening was the leading cause for medial UKA failure. This study aimed to observe short-term and midterm clinical outcomes following OUKA and determine whether tibial lesion affects the procedure clinical and radiographic outcomes. METHODS: Sixty patients (mean age 73.1 ± 6.6 years) diagnosed with SONK in the medial femoral condyle and treated with OUKA were separated into two groups using T1-weighted preoperative magnetic resonance imaging (MRI): group F (necrotic lesion confined to the femur) and group T (necrotic lesion spread to the tibia). The Oxford Knee Score (OKS), maximum flexion angle (MFA), and radiographic findings (radiolucent line and subsidence) were compared between the two groups using unpaired t-test. RESULTS: Both groups showed significant improvement in OKS and MFA values at the final follow-up, but without significant differences in the clinical and radiographic outcomes. CONCLUSION: OUKA is a reliable treatment procedure for SONK in the short and midterm. The presence of tibial lesions on preoperative MRI does not affect postoperative radiographic and clinical outcomes. Level of Evidence IV, Case Series.